This example writes goal position of the Dynamixel and repeats read present position until it stops moving. The funtions that are related with the Read and the Write handle the number of items which are near each other in the Dynamixel control table, such as the goal position and the goal velocity.

Available Dynamixel

All series using protocol 1.0

Sample code

/*
* ReadWrite.cs
*
* Created on: 2016. 6. 20.
* Author: Ryu Woon Jung (Leon)
*///// ********* Read and Write Example *********////// Available DXL model on this example : All models using Protocol 1.0// This example is designed for using a Dynamixel MX-28, and an USB2DYNAMIXEL.// To use another Dynamixel model, such as X series, see their details in E-Manual(support.robotis.com) and edit below variables yourself.// Be sure that Dynamixel MX properties are already set as %% ID : 1 / Baudnum : 1 (Baudrate : 1000000 [1M])//usingSystem;usingdynamixel_sdk;namespaceread_write{classReadWrite{// Control table addresspublicconstintADDR_MX_TORQUE_ENABLE=24;// Control table address is different in Dynamixel modelpublicconstintADDR_MX_GOAL_POSITION=30;publicconstintADDR_MX_PRESENT_POSITION=36;// Protocol versionpublicconstintPROTOCOL_VERSION=1;// See which protocol version is used in the Dynamixel// Default settingpublicconstintDXL_ID=1;// Dynamixel ID: 1publicconstintBAUDRATE=1000000;publicconststringDEVICENAME="/dev/ttyUSB0";// Check which port is being used on your controller// ex) "COM1" Linux: "/dev/ttyUSB0"publicconstintTORQUE_ENABLE=1;// Value for enabling the torquepublicconstintTORQUE_DISABLE=0;// Value for disabling the torquepublicconstintDXL_MINIMUM_POSITION_VALUE=100;// Dynamixel will rotate between this valuepublicconstintDXL_MAXIMUM_POSITION_VALUE=4000;// and this value (note that the Dynamixel would not move when the position value is out of movable range. Check e-manual about the range of the Dynamixel you use.)publicconstintDXL_MOVING_STATUS_THRESHOLD=10;// Dynamixel moving status thresholdpublicconstbyteESC_ASCII_VALUE=0x1b;publicconstintCOMM_SUCCESS=0;// Communication Success result valuepublicconstintCOMM_TX_FAIL=-1001;// Communication Tx FailedstaticvoidMain(string[]args){// Initialize PortHandler Structs// Set the port path// Get methods and members of PortHandlerLinux or PortHandlerWindowsintport_num=dynamixel.portHandler(DEVICENAME);// Initialize PacketHandler Structsdynamixel.packetHandler();intindex=0;intdxl_comm_result=COMM_TX_FAIL;// Communication resultUInt16[]dxl_goal_position=newUInt16[2]{DXL_MINIMUM_POSITION_VALUE,DXL_MAXIMUM_POSITION_VALUE};// Goal positionbytedxl_error=0;// Dynamixel errorUInt16dxl_present_position=0;// Present position// Open portif(dynamixel.openPort(port_num)){Console.WriteLine("Succeeded to open the port!");}else{Console.WriteLine("Failed to open the port!");Console.WriteLine("Press any key to terminate...");Console.ReadKey();return;}// Set port baudrateif(dynamixel.setBaudRate(port_num,BAUDRATE)){Console.WriteLine("Succeeded to change the baudrate!");}else{Console.WriteLine("Failed to change the baudrate!");Console.WriteLine("Press any key to terminate...");Console.ReadKey();return;}// Enable Dynamixel Torquedynamixel.write1ByteTxRx(port_num,PROTOCOL_VERSION,DXL_ID,ADDR_MX_TORQUE_ENABLE,TORQUE_ENABLE);if((dxl_comm_result=dynamixel.getLastTxRxResult(port_num,PROTOCOL_VERSION))!=COMM_SUCCESS){dynamixel.printTxRxResult(PROTOCOL_VERSION,dxl_comm_result);}elseif((dxl_error=dynamixel.getLastRxPacketError(port_num,PROTOCOL_VERSION))!=0){dynamixel.printRxPacketError(PROTOCOL_VERSION,dxl_error);}else{Console.WriteLine("Dynamixel has been successfully connected");}while(true){Console.WriteLine("Press any key to continue! (or press ESC to quit!)");if(Console.ReadKey().KeyChar==ESC_ASCII_VALUE)break;// Write goal positiondynamixel.write2ByteTxRx(port_num,PROTOCOL_VERSION,DXL_ID,ADDR_MX_GOAL_POSITION,dxl_goal_position[index]);if((dxl_comm_result=dynamixel.getLastTxRxResult(port_num,PROTOCOL_VERSION))!=COMM_SUCCESS){dynamixel.printTxRxResult(PROTOCOL_VERSION,dxl_comm_result);}elseif((dxl_error=dynamixel.getLastRxPacketError(port_num,PROTOCOL_VERSION))!=0){dynamixel.printRxPacketError(PROTOCOL_VERSION,dxl_error);}do{// Read present positiondxl_present_position=dynamixel.read2ByteTxRx(port_num,PROTOCOL_VERSION,DXL_ID,ADDR_MX_PRESENT_POSITION);if((dxl_comm_result=dynamixel.getLastTxRxResult(port_num,PROTOCOL_VERSION))!=COMM_SUCCESS){dynamixel.printTxRxResult(PROTOCOL_VERSION,dxl_comm_result);}elseif((dxl_error=dynamixel.getLastRxPacketError(port_num,PROTOCOL_VERSION))!=0){dynamixel.printRxPacketError(PROTOCOL_VERSION,dxl_error);}Console.WriteLine("[ID: {0}] GoalPos: {1} PresPos: {2}",DXL_ID,dxl_goal_position[index],dxl_present_position);}while((Math.Abs(dxl_goal_position[index]-dxl_present_position)>DXL_MOVING_STATUS_THRESHOLD));// Change goal positionif(index==0){index=1;}else{index=0;}}// Disable Dynamixel Torquedynamixel.write1ByteTxRx(port_num,PROTOCOL_VERSION,DXL_ID,ADDR_MX_TORQUE_ENABLE,TORQUE_DISABLE);if((dxl_comm_result=dynamixel.getLastTxRxResult(port_num,PROTOCOL_VERSION))!=COMM_SUCCESS){dynamixel.printTxRxResult(PROTOCOL_VERSION,dxl_comm_result);}elseif((dxl_error=dynamixel.getLastRxPacketError(port_num,PROTOCOL_VERSION))!=0){dynamixel.printRxPacketError(PROTOCOL_VERSION,dxl_error);}// Close portdynamixel.closePort(port_num);return;}}}

Details

usingSystem;

The functions Math.Abs(), Console.* for I/O, are in the example code, and it uses System namespace.

usingdynamixel_sdk;

All libraries of Dynamixel SDK are wrapped into the dynamixel_sdk namespace.

// Control table addresspublicconstintADDR_MX_TORQUE_ENABLE=24;// Control table address is different in Dynamixel modelpublicconstintADDR_MX_GOAL_POSITION=30;publicconstintADDR_MX_PRESENT_POSITION=36;

Dynamixel series have their own control tables: Addresses and Byte Length in each items. To control one of the items, its address (and length if necessary) is required. Find your requirements in http://support.robotis.com/.

// Protocol versionpublicconstintPROTOCOL_VERSION=1;// See which protocol version is used in the Dynamixel

Dynamixel uses either or both protocols: Protocol 1.0 and Protocol 2.0. Choose one of the Protocol which is appropriate in the Dynamixel.

// Default settingpublicconstintDXL_ID=1;// Dynamixel ID: 1publicconstintBAUDRATE=1000000;publicconststringDEVICENAME="/dev/ttyUSB0";// Check which port is being used on your controller// ex) "COM1" Linux: "/dev/ttyUSB0"publicconstintTORQUE_ENABLE=1;// Value for enabling the torquepublicconstintTORQUE_DISABLE=0;// Value for disabling the torquepublicconstintDXL_MINIMUM_POSITION_VALUE=100;// Dynamixel will rotate between this valuepublicconstintDXL_MAXIMUM_POSITION_VALUE=4000;// and this value (note that the Dynamixel would not move when the position value is out of movable range. Check e-manual about the range of the Dynamixel you use.)publicconstintDXL_MOVING_STATUS_THRESHOLD=10;// Dynamixel moving status thresholdpublicconstbyteESC_ASCII_VALUE=0x1b;

Here we set some variables to let you freely change them and use them to run the example code.

As the document already said in previous chapter, customize Dynamixel control table items, such as DXL_ID number, communication BAUDRATE, and the DEVICENAME, on your own terms of needs. In particular, BAUDRATE and DEVICENAME have systematical dependencies on your controller, so make clear what kind of communication method you will use.

Dynamixel basically needs the TORQUE_ENABLE to be rotating or give you its internal information. On the other hand, it doesn’t need torque enabled if you get your goal, so finally do TORQUE_DISABLE to prepare to the next sequence.

Since the Dynamixel has its own rotation range, it may shows malfunction if your request on your dynamixel is out of range. For example, Dynamixel MX-28 and Dynamixel PRO 54-200 has its rotatable range as 0 ~ 4028 and -250950 ~ 250950, each.

DXL_MOVING_STATUS_THRESHOLD acts as a criteria for verifying its rotation stopped.

// Initialize PortHandler Structs// Set the port path// Get methods and members of PortHandlerLinux or PortHandlerWindowsintport_num=dynamixel.portHandler(DEVICENAME);

portHandler() function sets port path as DEVICENAME and get port_num, and prepares an appropriate functions for port control in controller OS automatically. port_num would be used in many functions in the body of the code to specify the port for use.

index variable points the direction to where the Dynamixel should be rotated.

dxl_comm_result indicates which error has been occurred during packet communication.

dxl_goal_position stores goal points of Dynamixel rotation.

dxl_error shows the internal error in Dynamixel.

dxl_present_position views where now it points out.

// Open portif(dynamixel.openPort(port_num)){Console.WriteLine("Succeeded to open the port!");}else{Console.WriteLine("Failed to open the port!");Console.WriteLine("Press any key to terminate...");Console.ReadKey();return;}

First, controller opens #port_num port to do serial communication with the Dynamixel. If it fails to open the port, the example will be terminated.

// Set port baudrateif(dynamixel.setBaudRate(port_num,BAUDRATE)){Console.WriteLine("Succeeded to change the baudrate!");}else{Console.WriteLine("Failed to change the baudrate!");Console.WriteLine("Press any key to terminate...");Console.ReadKey();return;}

Secondly, the controller sets the communication BAUDRATE at #port_num port opened previously.

As mentioned in the document, above code enables Dynamixel torque to set its status as being ready to move.

write1ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 1 byte of TORQUE_ENABLE value to ADDR_MX_TORQUE_ENABLE address. The function checks Tx/Rx result and receives Hardware error.
getLastTxRxResult() function and getLastRxPacketError() function get either, and then printTxRxResult() function and printRxPacketError() function show results on the console window if any communication error or Hardware error has been occurred.

During while() loop, the controller writes and reads the Dynamixel position through packet transmission/reception(Tx/Rx).

To continue its rotation, press any key except ESC.

write2ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 2 byte of dxl_goal_position[index] value to ADDR_MX_GOAL_POSITION address. The function checks Tx/Rx result and receives Hardware error.
getLastTxRxResult() function and getLastRxPacketError() function get either, and then printTxRxResult() function and printRxPacketError() function show results on the console window if any communication error or Hardware error has been occurred.

read2ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, requesting 2 bytes of value in ADDR_MX_PRESENT_POSITION address. The function checks Tx/Rx result and receives Hardware error.
getLastTxRxResult() function and getLastRxPacketError() function get either, and then printTxRxResult() function and printRxPacketError() function show results on the console window if any communication error or Hardware error has been occurred.

Reading its present position will be ended when absolute value of (dxl_goal_position[index] - dxl_present_position) becomes smaller then DXL_MOVING_STATUS_THRESHOLD.

At last, it changes its direction to the counter-wise and waits for extra key input.

write1ByteTxRx() function orders to the #DXL_ID Dynamixel in PROTOCOL_VERSION communication protocol through #port_num port, writing 1 byte of TORQUE_DISABLE value to ADDR_MX_TORQUE_ENABLE address. The function checks Tx/Rx result and receives Hardware error.
getLastTxRxResult() function and getLastRxPacketError() function get either, and then printTxRxResult() function and printRxPacketError() function show results on the console window if any communication error or Hardware error has been occurred.